THBS1 and neuroblastoma: To investigate if THBS-1 promoter activity contributed to the difference of THBS-1 expression in the tumorigenic LA1-55n versus non-tumorigenic LA1-5s cells, a series of THBS-1 luciferase/promoter reporter constructs were used and transiently transfected into the phenotypically distinct NB cell lines (LA1-55n and LA1-5s).